This document summarizes what DEIMOS observers should do to
prepare for their observing run.
The DEIMOS slitmask cassette has 11 slots available, but since one
slot is dedicated to the focusing mask there are 10 slots
available for observer masks. Please plan accordingly.
Slitmask Due Dates
If you plan to use custom slitmasks during your DEIMOS run, plan
to begin the process early. Due dates depend on the complexity
of your mask designs:
- Standard masks (<200 slits):
design files are due at least 5
weeks prior to your run.
- Complex masks (>200 slits): files are due
at least 8 weeks prior to your run.
Mask Design Software
To begin designing masks, you'll need a working version of IRAF
with the official DEIMOS slitmask design package
DSIMULATOR. Please see our DSIMULATOR documentation for additional
information on installing and running the mask design software.
Once your slitmask designs are completed, you can submit them
for milling by using the
Slitmask Database Access page at UCSC via these steps:
Masks are now milled at the Keck summit, but in order to keep
the backlog of masks manageable we do require observers to
submit most masks 4 weeks in advance of the observing run;
please see the Slitmask Incentives
Protocol for details.
- Access to this page is restricted to known sites, so if
you find you can't access it, please contact the web page
() to add your site.
- Once you reach the site, please register to create your
account for submitting masks if you haven't already got one.
The system will email you a password which you should retain
for future reference.
- Enter your name, email address, and password to log in.
- Click on the Submit a Mask Design
File button to access the page for sending in your masks.
Important: verify your slitmask designs by checking the
online plot for each mask!
We now have a web
form for submitting your choice of DEIMOS gratings, filters,
and slitmasks. Please submit this information as soon as your
masks are milled. When specifying your list of slitmasks, please
note that the GOH_X mask is needed to complete the
afternoon focus procedure; it is selected by default on the web
form and you should include it in your mask list.
If you plan to observe in Hawaii and stay at either the Visiting
Scientists Quarters in Waimea or at Hale Pohaku on Mauna Kea,
please use the WMKO Lodging Reservation
Request form to make your arrangements. The VSQ in Waimea
sometimes fills up, so to avoid being sent off to Waimea Country
Lodge purgatory, make your reservation several weeks before your
If some or all of your observing team want to use one of our
sites to observe, please use our web form to submit a
request. All you need to do is log in to your WMKO
observer home page.
Your home page shows a list of any upcoming runs for which you
are the PI. For each run, there's a link which will take you to
the mainland observing request page. If you're not the PI, then
you can still submit a request by logging into your observer
home page and clicking the link that reads:
- Log in to the DEIMOS
Slitmask Database Access page at UCSC.
- Click on the Show Me My Mask
Inventory button to list your masks.
- For each mask, click the Plot
button to generate a plot of your mask. (Ignore any message
about the site's security certificate being invalid.)
- Inspect the plot and verify that all of your slits are
blue. Slits which cannot be cut (e.g., because they are too
small or lie are outside the legal milling area) are shown in
red. Slits which will not be cut because they are marked as
type "G" are shown in yellow-orange.
Example of good mask. All slits and alignment boxes
are blue, which means they will be milled, except for
two slits on the botton edge of the mask that are red,
i.e. will not be milled.
Example of masks with slits
of type "G". Most slits and
alignment boxes are blue, which means they will be
milled. However, there are several orange slits that
will not be milled,which can be hard to see if
you're not careful.
Example of BAD
mask. Slits are red, which means they WILL NOT
BE MILLED. Only the alignment boxes will be
milled. This mask should be deleted from the
database and re-designed. In this case, the slits
are red because the slit tilt is too big.
- If "bad" slits exist, consider redesigning and
resubmitting your slitmasks. If you do so, please use the
Forget button to remove your "bad" mask files so we do not
Click here to submit a mainland observing request
Please remember to generate and bring the following:
Within 24 hours after you submit your DEIMOS configuration
request, Keck's Summit
Instrument Activity Schedule will be updated to show the
slitmasks, filters, and gratings that are to be used on your
night. Please check this to verify that the configuration for
your night is correct!
- Starlist file.
- You must prepare a starlist file listing the RA/Dec
coordinates of your slitmask centers. When your file is complete, copy this file to your Keck
Create a starlist based on the output files from DSIMULATOR
- navigate to
ftp tools and right click on the deimos_starlist.py link and "Save as..."
python deimos_starlist.py *.fits or *.out files
that are the DSIMULATOR output files
- The resultant file is called starlist
- Upload your resultant list to Keck
- Guider finder charts.
- When you design your masks,
we highly recommend that you identify at least one star on the guider field for the coarse alignment
of the slitmask.
Coarse alignment stars:
The slitmask alignment tool now handles coarse alignment, so guider finder charts are less vital. If you want a guider finder chart:
- 15<R<18 magnitude
- Located on the guider's pickoff mirror (rather than reflected off of
- Slitmask plot.
optional plotfile from DSIMULATOR contains the coordinates and a sketch of
the TV field. It is helpful for troubleshooting alignment issues.
- Slitmask finder charts.
- It may be useful to have an image that identifies your alignment stars and slitmask targets if mask alignment initially fails.